Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Significant Accounting Policies [Line Items]
Assets, fair value disclosure	$ 0	$ 0
Liabilities, fair value disclosure	0	0
Restricted cash	64	64
Goodwill Impairment charges	0	0	0
Capitalized/deferred costs, amortization	960	668	344
Foreign currency translation adjustments	1,186	66	(409)
Net foreign currency transaction gains (losses)	(1,139)	(24)	155
Advertising expense	11,097	6,471	3,632
Deferred Commissions
Significant Accounting Policies [Line Items]
Capitalized/deferred costs	8,945	6,798
Capitalized/deferred costs, amortization	6,119	4,693	3,556
Capitalized/deferred costs, net of amortization	11,747	8,893
Capitalized In-Vehicle Device Costs
Significant Accounting Policies [Line Items]
Capitalized/deferred costs	402	2,260
Capitalized/deferred costs, amortization	960	668	344
Capitalized/deferred costs, net of amortization	$ 3,782	$ 4,149
Internal-use software
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	3 years
Customer Relationships | Minimum
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	3 years
Customer Relationships | Maximum
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	9 years
Customer Relationships | Weighted Average
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	6 years
Trademarks | Minimum
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	3 years
Trademarks | Maximum
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	9 years
Acquired Developed Technology | Minimum
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	3 years
Acquired Developed Technology | Maximum
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	9 years
Patents
Significant Accounting Policies [Line Items]
Intangible asset, estimated useful life	20 years
In-vehicle devices | Minimum
Significant Accounting Policies [Line Items]
Property plant and equipment, useful life	4 years
In-vehicle devices | Maximum
Significant Accounting Policies [Line Items]
Property plant and equipment, useful life	6 years